Photocell mounting device



March 10, 1953 B. E. SHAW 2,631,247

PHOTOCELL MOUNTING DEVICE Filed Sept. 17, 1949 70 l 1. s9 7| l I 66 1 IL1J 64 TnVE 1110 r sumo/v E. SHAW AHUT'TIEJ Patented Mar. 10, 1953UNITED STATES PATENT OFFICE PHOTOCELL MOUNTING DEVICE Burton E. Shaw,East Boxford, Mass., assignorto Photoswitch, Incorporated, Cambridge,Mass.., a corporation ,of Massachusetts Application September 17, 1949,Serial No. 116,393

4 Claims. 1

This invention relates to devices for mounting and testingradiation-sensitive elements such as photoelectric cells.

In many types of photoelectric controls, provision must be made forperiodically checking the operation of the detecting photocell undercertain standard test conditions. A fixed spatial relationship betweenthe cell and the test light source is one of the requirements. In mostoperating installations compactness, simplicity of mounting, andprotection of the cell from dirt, dampness, vibrations, and mechanicalshock are also important considerations.

The object of the invention is to provide a self-contained, compact andinexpensive mounting and test fixture which is suitable for checking andtesting the-operation of the cell under known conditions, which insuresmaximum life of the cell by cushioning and protecting it againstmechanical damage, which minimized stresses due to unequal thermalexpansion of the various members, and which allows for selection of thefrequency and direction of radiation to which the cell is exposed.

The mounting device here described is suitable both for comparativetesting of different cells, and for periodic testing of .a particularcell, either as an experimental fixture or as a permanent operatinginstallation.

These and other objects, improvements and novel features of this devicewill be more apparent from the following detailed description:

In the accompanying drawings,

Fig. 1 is a plan view of the mounting device;

Fig. 2 is a side elevation;

Fig. 3 is a bottom. view;

Fig. 4 is a cross-section along line 4--4 of Fig. 1;

Fig. 5 is an isometric view, partially in section, of the insulatingbase member;

Fig. 6 is an enlarged view showing an alternate construction for holdingthe connector plate to the housing;

Fig. '7 is a partial View of the device showing an alternativeconstruction of the filter shield.

The mounting device consists generally of a filter shield, secured to abase which houses an insulating support for the photoelectric cell and amultiple connector of conventional type for external wiring, a mountingfor an electric light bulb near an aperture in the base in fixedrelation to the cell, and suitable resilient cushioning members at thecontact points between the cell and the housing.

As shown particularly in Figures 1, 2, 3, and

2 4, the photocell 66 is housed in-a dome'shape shield l0 made ofsuitable material such as-glass or plastic. The shield may be made offilter glass adapted to transmit only a selected band of frequencies ofradiation, for example, infrared, and terminates at the bottom in anoutwardly projecting flange l2. A generally cylindrical housing base 18,preferably of cast aluminum, is fitted at the bottom with a flangedconnector plate 20 fastened in place by screws 2 I. A threaded fitting23 for mounting the device is fastened to plate '20 by rivets '22 andcarries a tripole connector 24 of conventional type with terminals 26,28, 30 properly aligned. The connector is fixed against rotation infitting 23 by the head 32.

A projection 34, which-is cast as an integral part of the housing baseI8, is internally recessed and'has an opening 36 in its upper face. Theopening is covered by test window 38, which iscushioned against a metalshoulderby a rub-1 ber ring 40 and fastened in place, preferably,by

spinning over the surrounding rim. 1

The opening 36 communicates with the rec'es 4|, which houses test lamp42, so inclined as to shine on the shield Ill. The base rim 44 of thetest lamp is electrically grounded. The lamp is held in place against ashoulder in the recess 4| by an electrically conductive leaf spring 46which also serves as the electrical contact with the center terminal ofthe test lamp. The lower end of leaf spring is connected to the tripoleterminal 26.

The housing base l8 contains an annular insulating base block 48 (Figs.4 and 5), which is shouldered top and bottom to form a flange 60. Thelower rim of the block fits over flange 50 of connector plate 20. Aclearance hole in the block 54 accommodates the leaf spring 46. Alocating pin 55 is fixed to the lower surface of the block and engages alocating recess in connector plate 20. Another pin 58 on the upper sideof the flange 60 engages a locating notch in the bottom flange of theshield ID to prevent relative rotation of the members. The reduced neckportion 62 carries an internal shoulder 63 which holds a washer 64, ofresilient material, such as rubber, for cushioning and supporting thephotocell 66. Terminals 6'! and 68 of the photocell are connected toterminals 28 and 30 of the tripole connector, preferably by soldering inthe case of a permanent installation. Enough slack is left in wires 61and 68 to permit assembly of the members.

The upper end of the cell 66 is held in a recessed washer 69, of rubberor other resilient material, against the inner wall of the shield l0. Acoil spring 10 compressed against the upper surface of the washer 68 andthe top of shield 10, provides the pressure to keep the photocell 66firmly seated between washers 64 and 69, and to hold the flange 12 ofshield l against the gasket I4 which is retained by inner shoulder 16 ofthe base 18. This resilient mounting of the photocell and shieldminimizes the stresses imposed on the fragile parts by vibration,mechanical shock, and temperature changes.

, The photoelectric cell is positioned in the housing so that itsradiation-sensitive element H faces the test window 38. While thearrangement of the element ll gives the cell a directional inwardprojecting flange; a dome-shaped shield having on its lower edge anoutward projecting flange adapted to engage the flange on said base; aphotocell mounted within said housing; a spring compressed between theend of said cell and said shield so as to maintain said cell, saidshield, and

. said base in engagement; and a projection in the characteristic, thefield of observation of the cell I may be further restricted by paintingor covering on the filter shield H1, except for a window '12, as shownin Fig. '7.

; The connector plate 29 may be fastened to the housing base l3 as shownin Fig. 6 by spinning over the bottom rimof base 18. A gasket 16 isinserted between the flange M and the shoulder T! to insure a tightseal.

I Since certain changes may be made in the above-described article anddifferent embodiments of the invention could be made without departingfrom the scope thereof, it is intended that all matter contained in theabove description or shown in the accompanying drawing shall beinterpreted as illustrative only and not in a limiting sense.

What is claimed is:

1. A mounting device for photocells, which comprises: a hollow housingbase-carrying an inward projecting flange; a shield having an outwardprojecting flange arranged to engage the flange on said base; means formaintaining said flanges in engagement; a photocell supportmounted-within said housing; and a projection in one side of saidhousing base,said projection side of said housing base, said projectionbeing internally formed to provide a means for mounting an electriclight bulb and having an opening in the direction of the sensitiveelement of said photocell.

4. A device according to claim 3 having a multipole connector fixed tosaid base, and having a leaf spring attached to one of the contacts ofsaid connector adapted to engage one of the external contacts of saidbulb.

BURTON E. SHAW.

REFERENCES CITED The following references are of record in th file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,116,048 Farber Nov. 3, 19142,013,095 Friend Sept. 3, 1935 2,169,818 Scott Aug. 15, 1939 2,337,401Miller Dec. 21, 1943 2,458,048 Bauman Jan. 4, 1949 FOREIGN PATENTSNumber Country Date 773,398 France Sept. 3, 1934

